Having moved from 18 years of all-electric coil cooking to gas a year and a half ago, I have an observation on disk versus ply that is different from others. Most of my pans are All-Clad stainless, as I also have an induction top so I want most of my pans to work on both the induction and gas. However, I have a few pieces of other stuff, some all-aluminum, and a couple of pieces of disk-bottom cookware. In my experience, disk-bottomed cookware is great on electric, as all the heat enters the pan through the bottom. The pan's thick bottom distributed the heat well across the bottom, better than with the All-clad, which is thinner. However, I had problems using the disk-bottomed cookware on my gas range. The gas burner sends a lot of heat up the side of the pan, which caused the area just above the disk to become much hotter than the rest of the pan, and caused things to burn. It is obviously fine for boiling water, but then plain think alumnum would work better because of increased conductivity. The tri-ply All-Clad does much better on gas, as the laminations are all-around the pot, preventing hot spots. So, in my opinion, in general, thick disk-bottom pans are best on electric heat sources for even distribution, but ply cookware works better on gas, to prevent hot spots from forming at or near the disk-pan joint.

I have a few french copper pots my mother gave to me after she got her AGA (they don't have machined flat bottoms so they don't work on the AGA well). I LOVE them. I was fortunate enough to check out Tuesday Morning last week, as they advertised Cuisinart copper pots and pans (I have tons of stainless muulticlad cuisinart and I love it, more than my All-Clad). I bought a couple open stock pieces, and happen to find a 7-piece set for $49.99, so I grabbed it. After looking at my reciept, I realized it had be mismarked as a cheap suitcase, which is why a set with a MSRP of $900 sold for $50! If you have a Tuesday Morning in your area, give them a look, as it was a featured item (but they sell out these types of things fairly quickly).

For heat focused towards the middle of a pan for residential stove, there are two sample videos on youtube that demonstrate the subject. First one is from trevor@eurostoves who compares a dual ring sealed burner with a modified one with a seal cap removed. Trevor shows that the modified one boils water more rapidly. Another video is in dutch, an advertisement video for the gas hob that I have. At 2.36 mark, Chef Réne demonstrates an effect of focusing heat towards the middle of round bottom wok versus heat from outer ring. Spec-wise, inner wok ring is rated only at 3kw (~10k BTU) while the outer ring is rated at 6kw (~21k BTU) comparable to the outer ring from Wolf in the above video as well as many other 5" dual ring wok burners on the market. What he shows is that water boils more vigorously when heat using inner ring, and water barely boils when outer ring is used. I have these Asko/ATAG hobs in my kitchen and can attest wok cooking with round bottom wok is better when using more focused heat inner ring flame compared with using larger, higher rated heat output outer ring flame. Food sears quicker, water evaporates faster. Despite saying that, it is still a residential stove where portion control is critical. It won't handle large amount of food being dumped into the wok. However, when cooking with the right amount of food, generally around 2-4 serving size for multiple plates meal, there is a good amount of wok her to be had from this hob. Cooking with flat induction hob with round bottom wok and wok ring adapter also works similarly to a degree in that heat is more focused towards the bottom of the wok. One critical element is to find the right combination of wok shape and adapter ring such that the bottom does not sit too close nor too far from the induction surface. When it is too close, heat control can be a bit more difficult.

The bad news was that it was impractical to bring a gas line to the island (more of a penninsula really) in our kitchen where the cooktop is located. Yes, we tried everything we could think of, but we have a slab foundation (common for Southern California) and our roof design prevented running a line to the roof and down to the wall next to the cooktop. Only option was to knock a 10 foot long hole in the kitchen wall, which we didn't want to do. Thus we had to continue using electric. After a lot of soul searching, we decided to replace the Thermador units with a new Kitchenaid downdraft and black glass cooktop. The age of the existing units (which I've had to repair on my own on occassion) were major factors in the decision. I found the installation to be surprisingly easy, though I did have to do a lot of cutting of the interior of the island to make it fit. The downdraft is superior to the old Thermador (much taller when extended) and while it does have an internal fan I also kept the original Thermador external blower on the roof (I cannibalized the controls and built an auxillary switch under the cabinet). This gives me the option of running the roof blower when I want quieter operation. As for the cooktop, well, I'll probably never get used to a new style black glass type. Far more maintenance that the old Thermador coil radiant unit, and I find it nearly impossible to see where the cookrings are without strong light. Coil units are obvious where the hot places on a cooktop are, glass radiant are not, as my many burnt pot holders will now attest. I'll live, but for you folks deciding to move away from coils, then do whatever you have to do to get a gas line to your new cooktop. Selling your first born child might not be too high of a price.... Cheers, Nick in Palm Springs